US2666472A

US2666472A - Apparatus for making heat sealed ruffled articles

Info

Publication number: US2666472A
Authority: US
Inventors: Lee C Hosfield
Original assignee: Union Carbide and Carbon Corp
Current assignee: Union Carbide Corp
Priority date: 1946-12-07
Filing date: 1950-10-18
Publication date: 1954-01-19
Anticipated expiration: 1971-01-19

Description

Jan. 191954 L. c. HosFlELD APPARATUS FOR MAKING HEAT SEALED RUFFLED ARTICLES Original Filed Dec. '7, 1946 3 Sheets-Sheet l lNvENToR LEE C. HOSFIELD ATTORNEY L. C. HOSFIELD Jan. 19, 1954 APPARATUS FOR MAKING HEAT SEALED RUF'FLED ARTICLES Original Filed Deo. 7, 1946 3 Sheets-Sheet 2 lNvENToR LEE C. HOSFIELD BY Jan. 19, 1954 l.. c. HosFlELD APPARATUS FOR MAKING'HEAT SEALED RUFFLED ARTICLES Original Filed Dec. 7, 1946 3 Sheets-Sheet 3 Moveable 'horz'fzg Slug xNvEN-rofz LEE C. HOSFIELD Patented Jan. 19, 1954 UNITED STATES aan ATENT OFFICE APPARATUS FOR MAKING HEAT SEALED RUFFLED ARTICLES Lee Hoseld, Parma, Ohio, assigner, by mesne assignments, to Union Carbide and Carbon Corporation, a corporation of New York Claims. (Cl. 154-15) This invention relates to novel unitary heatsealed ruies and rullied articles made from thermoplastic dielectric materials, and to a novel process and apparatus for making such unitary rufiies by spot-welding together succesive foldedover portions of ruined films, sheets, fabrics or other sheet-like elements of thermoplastic dielectric materials and, if desired, concurrently spot-welding successive folded-over portions of the latter articles to another sheet, lm, fabric or other sheet-like element made from the same or another thermoplastic dielectric material.

A large variety of articles such as raincoats, aprons, umbrellas, window curtains, shower curtains, dry goods Sundries and the like now are being made from thermoplastic resinous dielectric materials. In the manufacture of such articles it is common practice to unite the margins of two or more lms by sewing the margins together, using thread of suitable material. Such operations involve the repeated puncturing of the sheeting by the fabricating needles at closely-spaced points, thereby weakening the material at and adjacent the seam. Moreover, the seam produced is stiff and incapable of yielding when subjected to stretching forces, so that sudden stresses sometimes tear the thread from thesheeting or break the thread after only a slight elongation of the lms. This method of fabrication is not satisfactory, particularly for articles where strength, durability, or imperviousness to water or other liquids and gases are required.

For the purpose of providing a stronger article, processes have been developed whereby sheets or lms to be united have flat overlapping margins pressed together to form a seam while being heated to suitable temperatures. Heat and pressure are applied by means of heated cooperating pressure rolls to form a continuous welded seam.

In recent years the so-called electronic method of heating has assumed importance as a source of the welding heat. Opposed pressure rolls serve as rotating electrodes in a high frequency electric circuit. The thermoplastic dielectric materials, while continuously pressed between the electrodes, are subjected to a high frequency electric field, thereby being softened and welded together. Continuous narrow welded areas which readily are visible are thus formed. Such methods reduire that the sheets to be united are of uniform thickness and free from wrinkles, etc.

There are a wide variety of articles made from thermoplastic dielectric materials which, to be satisfactory for the intended use, require the aixing to a sheet, film or fabric made of or containing a coating of a thermoplastic dielectric material, of ruffles of the saine or an equivalent material. Among such articles may be mentioned window curtains, shower curtains, aprons and other articles of wearing apparel, shelf and table decorative strips and covers, and the like. fijnere also is a demand for unitary ruilled articles made from such dielectric materials.

lt is highly important that such ruilled articles have an attractive appearance and be of a uniform construction. The ruffled structure must be strong, tough, permanent, and sufliciently elastic to yield when subjected/to tensile or to puncturing forces without being injured or destroyed. The present invention is concerned with such a ruied article and with the novel method and apparatus for its production.

Among the more important objects of the invention are the following: to provide a novel unitary ruffled article made entirely of thermoplastic dielectric material; to provide an unperforated heat-sealed ruffle or ruied article of dielectric material, and one which is free from restricting threads of dissimilar material; to provide a ruffled article wherein the sides of each ruffled area formed in a dielectric thermoplastic material are permanently united to each other and to an adjacent ruffled area, and, if desired, to a base sheet, by a plurality of spot welds to provide a rui'lied composite article wherein each individual fold of the ruie is of uniform size and is spot welded to the base sheet and to an ad- `iacent fold at one or more spaced points of limited area; to provide such a unitary heatsealed ruffled article which can be elongated more than of its original length without rupturing the ruffled structure or the seam; to provide heat-sealed ruiiles having stronger bonds between the base sheet and the ruffle and greater resilience along the line of the -ruie than ruled articles made by sewing with thread; to provide novel ruiled articles wherein repairs to the ruiiles can be made merely by spot-welding without loss of the ruilied material; to provide in novel manner for the production at high rates of thermoplastic sheet-like articles having permanently united therewith strong welded-on ruliies, uniform and pleasing in appearance, and having good physical properties; to provide a novel process and apparatus for continuously producing thermoplastic articles having welded-on ruiles whlle preventing injury to the ruied material' to provide a novel process and apparatus for weldmg rules of a dielectric material upon a 3 base sheet of such a material by means of a high frequency electric field, while inhibiting arcingr at the electrodes and burning of the material; and to provide in novel manner for the continuous spot-uniting of ruffled sheets, films, fabrics or the lilre made from or containingr dielectric thermoplastic materials with other sheets, films, or fabrics made from or containing the same or other thermoplastic dielectric material, either plasticized or unplasticized, ormade fromxpaper,l

cloth and like materials coated with such a dielectric material.

The invv-ntion especial utility for the production of strong, permanent, yielding ruf'les and ruffled articles having elastic properties made from such plasticized thermoplastic. materials as the cellulose esters and ethers, such as cellulose acetate, viscose, regenerated cellulose and ethyl cellulose; vinyl resins, such as the polyfvinyl chlorides, the polyvinyl acetates, copolymers of vinyl chloride and` vinyl acetate, polyvinylidene chloride resins, polyvinyl alcohol resins, polyvinyl acetal resins, polymethacrylate resins, and copolymers of vinyl halides and acrylic compounds, such as copolymers of vinyl chloride with acrylonitrile, with acrylic acid, and with the acrylic acid lower alkyl esters; copolymers of butadiene with styrene and with acrylonitrile; resinous reaction products of a diamine and a dicarboxylic acid.

A preferred form of the novel articles of the invention generally involves a base sheet, silk, fabric or other sheet-like element of a tlrermon plastic synthetic resin or other dielectric material which is permanently united by one or more series of spaced spot welds with a sheetlike element of the same or other thermoplastic dielectric material having the form of a continuous succession of interconnected folds or ruillcg of uniform size and shape. The respective sides of each folded aree, are permanently united with cach other, with a side of the next adjacent.

folded area, and with one or more layers of the base sheet by means of atleast one spot weld, and preferably two welds, covering a small portion of eachsuch folded area. Since the individual folds are not secured by restricting non-elastic sea/ed threads, the entire body of the welded rutile or the composite article is free to yield under tension andto elongate or stretch, the extent of such elong tion boing dependent upon the character the material from which the sheetlike elements are made, the number, area and character of the spot Welds, upon other factors. In the case of articles made from sheets of vinyl resins, such as those produced by the copolymerisation oi a vinyl halide with a vinyl ester of a lower aliphatic acidwe. g., a vinyl chloride-vinyl acetate copolymer containing between '70% and 95% of the chloride in the polymer--the heat-sealed ruffled article can be elongated more than 90% of its original length without rupturing the welded seam and, when tension i5 released, will regain its original length. The bond between the base sheet and the ruiiled sheet is from GG to 99 et stronger than that secured in the same article by sewing with thread.

Since each of the folds is unrestricted by. threads, the peak of each fold is free to pucirer outwardly from the base sheet and to give to the ruiiled article aA uniform, pleasing appearance. The folded areas are not noticeably deformed by the welding heat and pressure used.

lf, when such a ruffled article is subjected to excessive stress, one or more of the spot welds fl fails, the ruffles still are held in place and the appearance and the strength of the ruffled structure are preserved by the remaining7 spot welds adjacent those which failed.

The novel ruffled articles are made, in accordance with a preferred form of this invention, by a novel process and apparatus which forms a rapid succession of similar rufiies or folds of the desired size and shape in a sheet-like element of suitable dielectric material and, as rapidly as each such ruffle or fold is formed, the sides of such fold are permanently spot-welded to each other and to a surface of a next adjacent fold., and preferably toY one or more layers of a suitable sheet-likebase element, at from one or two or more spaced points of limited area in such fold. The Welding is effected by the use of localized heat and pressure. The heat is produced locally in the material at each successive folded area by bringing such areas between two electrodes to which a. high frequency electric c rrent of suitable voltageis applied, as hereinafter more particularly described.

In the accompanyingT drawings wherein are illustrated certain preferred forms of the invention,

Fig. 1 is a diagrammatic view of one form of apparatus of the invention, parts being omitted;

Fig. 2 is a side elevation of one form of heatsealing machine showing the electrodes, electrode reciprocating mechanism, and associated parts, parts being broken away, and other parts being omitted;

Fig. 3 is a schematic wiring diagram of another high frequency heating circuit and associated parts;

Fig. 4- shows diagrammatically the relationship between the actuating cam` for theV reciprocating electrodeand the rotary tuning device of Fig. 3;

Fig. 5 illustrates two alternate forms oi' tuning stubs or impedance matching means for the high frequency heating circuit;

Fig. 6 is a fragmentary plan view of a folding and indexing blade for forming Vthe ruffles;

Fig. 7 is a perspective fragmentary view of a reciprocatable electrode and operating stem;

Fig. 81 shows one preferredA form of. ruiled; com,- posit'e article of the invention;

Fig. 9 shows another form of the ruiiled composite article;

Fig. I0 shows a unitary ruilled heat-sealed strip reinforced by a folded-over end margin; and

Figs.. 11' and l2, respectively, show other forms of composite ruflied articles of the invention.

Referring toFigs. 1 and 2 of the drawings, the4 apparatus comprises an operating head H which conveniently may be mounted on a table T, generally similar to the operating head and table of the standard type of sewing machine. Secured to the lower endv of va member I I mounted on the head H for longitudinal recprocation are one or more upper electrodes I3 adapted to cooperate with corresponding stationary lower electrodes I5 aligned therewith and formed on an electrode plate IB- secured below the table top in suitable manner and insulated from the latter by a plate I1 of a dielectric material such as polystyrene; A rider I8 secured to member I I slides in a groove in a guide member I2 and prevents turning of the member I I.

For passing a high frequency electric current through a plurality of layers of one or more-sheets.

of thermoplastic organic dielectric material while in the space between the electrodes to heat such material to a welding temperature, the electrodes are in a high frequency electric circuit which comprises an oscillator or generator I9 or other source of high frequency electric current. One terminal of the high frequency output line is grounded through a line 2i). The other terminal is connected with the stationary electrode plate iii through a coaxial transmission line, the outer conductor ila of which terminates in the outer tube 23 of a tuning stub 26 such as shown in Fig. 5. The inner conductor 2| terminates in a coaxial inner rod 23a of the stub 25. A coaxial variable capacitance 24 connects the tube 23 and rod rita within the said tube. Tube 23 is grounded through line 25. A short circuiting member 26a fixes the length of the short circuited stub. The electrode i3 is grounded through a flexible strap 2l.

For reciprocating each electrode I3 in a iixed path toward and from a corresponding stationary electrode l5, a standard electric motor 29, equipped with a magnetic brake for instantaneous starting and stopping and of a type oommonly used on industrial sewing machines, drives a rotatable shaft BI through pulleys 33 and 35 and V-belt Si. Shaft 3| drives an upper shaft 39 through pairs of beveled gears 49, 49, and 4I, lil, and vertical shaft 43. Secured upon one end of shaft $9 is a cam plate 45 having a groove in one face providing a cam surface 41. A cam follower ad is mounted for rotation on a pin secured upon a follower block I. The latter is secured for vertical adjustment upon reciprocatab-le rod II and has rigidly connected therewith the electrode or electrodes I3. By means of a set screw E2 in block 5I the latter can be secured at a selected point along the rod II and thus determine the pressure applied upon the thermoplastic material by each electrode I3 when the latter is in the lowermost position during a spot-welding operation. A compression spring 53, operatively interposed between a pin or flange on rod Il and a fixed part of the operating head H, continuously exerts a downward pressure upon the reciprocating rod during operation and prevents backlash.

For feeding a strip or sheet of dielectric material M from a source of supply thereof and for forming a succession or ruliles or folds therein adjacent the welding or heat-sealing zone a pair of feeder rolls including an idler roll 55 and a roll 5E driven by a motor 51 draw a sheet of such material from a supply roll 58. The sheet then is directed around a dancer roll BI and idler rolls 62, 62 and 52 and thence between a xed margin fold-over guide 63. It then is moved intermittently to the welding zone between the electrodes i3, i5, by means of a ruifling mechanism R. The dancer roll 6i is rotatably mounted upon an end of a rod 59 which is pivoted about a fulcrum td. Mounted on the end of rod 59 opposite roll Sil is an adjustable counterweight, and a mercury switch 84 of Well-known type having terminals connected in the electrical circuit driving motor 5l'. The arrangement is such that when the roll Si is in the position shown in full lines in Fig. 1, the switch 64 cuts oif current to motor di, and that when roll 6I is in the position shown in broken lines the switch closes the circuit and drives motor 51. Thus, any diiferences between the rate of unwinding of material from the supply roll and the rate demands of the ruffling mechanism are equalized.

For feeding a sheet M, with or without a base sheet or lm B, of thermoplastic dielectric material between and past the electrodes at a welding or heat-sealing zone, a resiliently mounted presser foot @l cooperates with a vertically and laterally movable feed dog 'de while pressingly engaging the sheets interposed therebetween. The feed dog has a serrated surface area adapted intermittently to contact the underside of the ruffled sheet or the composite sheet B and move the same to the left in Fig. 1 away from the welding zone. Thereafter the feed dog is depressed and withdrawn from contact with such sheet and moved to the right toward the Welding Zone. For effecting such feed of the sheet or sheets the presser foot El is secured to a rod 6B mounted on the head H for movement toward and from the feed dog E55. An adjustable compression spring 'it presses the foot El upon the sheets lying upon the feed dog under a selected pressure. A cam member 'il pivoted on the head H cooperates with a member i2 secured to rod 53 for raising and lowering the rod t8 and for locking it in raised position. For effecting intermittent movement of the feed `dog and the sheets lying between it and the presser foot in a direction from the welding zone, as shown diagrammatically in Fig. l, the feed dog ESS is secured to an arm '13 which is connected with a crank i4 secu-red upon the shaft 3L The crank arm 'Iii is pivoted upon an end of a rocker arm l5, the other end of which is pivotally connected with a xed support. In the form shown in Fig. 2, the feed dog is secured to a plate 'ifi which has an end pivotally secured to the arm '15. A cam member Ti mounted on shaft 3l cooperates with a cam groove in the plate l5 during rotation of the shaft. The cam member is pivotally connected with arm *1:3 through arm i3. During operation of motor 29 the rotation of shaft 3! and crank i4 causes the feed dog 59 successively (l) to rise vertically and engage the sheet M or B, (2) to move to the left to index the ruiiled article, then (3) to retract downwardlj,7 from the sheet and (4,) to move toward the right while disengaged from the latter; and to repeat this cycle of motions for every rotation of shaft 3|. The movement of feed dog Se is timed so that it advances the ruflied article to the left a selected distance just before each forward movement of the foldindexing mechanism to be described.

For forming in sheet M a succession of rufes of uniform size and spacing at a uniform rapid rate, a crank plate 79 secured upon shaft 3e is operatively connected, by means of a rod 8@ and a clevis Iii with a lever arm 32 secured upon a rocker shaft 83 suitably supported on the operating head. When shaft 39 is rotated the rocker shaft 83 oscillates through a selected arc, depending upon the position of clevis iii along the arm 82 maintained by means of a clevis pin cooperating with one of the apertures in arm 82. Secured to an-end of rocker shaft 83 is a lever arm 84 which supports an adjustable folding and indexing blade d5. The latter is pivoted upon ears formed on the lever arm 94, and has a rear flange portion cooperating with a spring 85 carried by that arm to urge the blade 85 downwardly against the sheet of material under a regulated tension. The forward end of the blade has a serrated margin and has therein slots Si (see Fig. 6) adapted to accommodate the eleotrodes I3, I3. The arrangement is such that blade 85 is held in retracted position to the right (see Fig. 2) away from the electrodes i3 during the welding part of each cycle of operation, and

then advances .to the left during thepart of the cycle when electrodes I3, I are held apart, thereby moving fresh sheet material into position between the spaced electrodes and forming therein a fold or pleat. A stationary serrated blade 85 prevents retraction of the sheet M when blade 35 is retracted, and prevents folds being formed in sheet B. A folder guide 63 adjacent the folder guide 63 folds over a margin of the base sheet as it moves to the welding zone.

The fold or pleat produced can be varied in size, and the number of folds or pleats per inch can be regulated, by the adjustment of the length of stroke of the arm 84. To increase or to reduce the number of folds per inch, clevis 8| is connected with arm 82 at a point further from or nearer to shaft 83, respectively. Preferably the adjustment is such that from six to eight rules or folds per inch are produced, although articles having from four to twelve folds per inch readily are made. However, the ruflled areas should be at least one-sixteenth of an inch in width in order to insure the spot-welding of each rule at one or more spaced points even in in stances where some stretching of the materialresults from action of the folder blade 85 or of the feeder foot 59.

The actual welding portion of each cycle of operation, during which the electrodes I3, I5, or respective pairs thereof, exert pressure upon the folded-over portions'of the ruffle material, .and upon the base sheet when present, constitutes about three-fourths of the cycle and is governed by the shape of the cam surface 41. The welding of the ruffled article is accomplished during this time by passing through the layers of material at the spot-welding zone between the electrodes a high frequency current of from to 500 megacycles and at suitable voltages, e. g., around 1,000 volts at 60 megacycles.

In the form of the invention illustrated in Fig. 1 using frequencies of 50 to 500 or more megacycles, the tuning stubV 26 of standard construction, the variable capacitance 24 and the interconnecting lines define a matching circuit having impedance that can be varied to accommodate various load impedances and to provide maximum power transfer to the work.

Tuning stubs of the type shown in Fig. 5 are particularly useful as matching sections when employing frequencies of around 100 to 200 or more megacycles. Such tuning stubs are in the form of a coaxial transmission line connected with the high frequency generator. The outer conductor of the coaxial line is a brass tube 90 and the inner conductor is a brass rod 9|. Two brass sleeves 03, 94, serve as terminals of the transmission line, one sleeve sliding upon the outer conductor 90 and the other sliding on the inner conductor 9 I. The length of the short circuited portion is adjusted by means of a brass disc 95 which slides along the inside of the outer tube but also contacts the inner rod 9|. The length of the load end is adjusted by sliding the

respective terminals

93, 94 along the tubes and rod.

In another form of tuning stub illustrated in Fig. 5, the movable shorting disc 95 is replaced by a fixed shorting disc 96 (shown in dotted lines in Fig. 5), so that the length of the short circuited stub is fixed. The points of the transmission line termination at the tube and rod also are fixed. A coaxial variable capacitance 91 (shown in dotted lines) is set within tube 90 and is connected across

theconductors

90, 91|.

Fig. 3 illustrates schematically a. form of circuit particularly useful withv frequencies of around 50 to 100 megacycles. It effectively prevents arcng at each electrode I3 as the latter is rapidly withdrawn from the welding zone, by throwing the high frequency circuit out of resonance from a time just prior to the withdrawal of electrode I3 from pressing contact with the work until after the electrode is in contact with another ruille in the next succeeding cycle of operation.

If desired, the circuit can be detuned in various ways during such period of each cycle to accomplish this purpose. In the form of the invention shown in Figs. 3 and 4, the circuit comprises a highfrequency generator I9 having one terminalZU grounded and having its other terminal connected in series through line 22 with a fixed inductance |05, a variable condenser V and the lower electrode plate I6. A line |06 having therein a fixed inductance |01 connects line 22 to ground. The condenser V has segmental rotor plates 99 subtending an are of 90, mounted upon a rotatable shaft I0!) having an electrically insulated portion Illa and driven from shaft 3| through a pair of bevel gears I0 The condenser has fixed plates 02 `with cutaway segmental portions somewhat greater than the width of segmental plates 99, and preferablysubtending an arc of 120. Y

Fig. 4 more clearly indicates the function of the detuning variable condenser, wherein it is shown in full lines in the position during which a fold is being formed and moved into position between the electrodes and the high frequency circuit is out of resonance. One position of the plates 99 during the welding stage of each cycle is indicated in broken lines. The use of this condenser permits the use of optimum -voltage duringV the welding stage of each cycle, while limiting the .voltage during the balance of the cycle to one insufficient to cause arcing or burning of the materials.

Fig. l also illustrates the general shape of the rotary cam 41 which, in conjunction with spring 53, controls the reciprocation of rod Ii, and the period of its dwell in a position with electrode I3 in welding position. As shown, this cam and the cam follower 49 raise and lower electrode |73 in a vertical patternV during one-fourth of a cycle, andv then, with the aid `of spring 53, hold the electrode in pressure contact with the ruffled material during the balance of each'cycle. Through correlation of the timing of the respective `movements of the cam 41, .the folder blade and the feeder foot 59, the successful production of welded ruffled articles having eight ruffles per inch, each ruffle being concurrently spot-welded in two zones, has ybeen accomplished at the rate of 34 feet per minute. This corresponds to the productionof 3,264 single welds per minute or, when using two pairs of electrodes, 6,528 welds per minute.

In performing the process using the apparatus of Figs. 1 and 2, the leading ends of the respective base sheet B and ruille element M are placed in mutual contact above the feeder foot 69 and between the electrodes, and motor 29 is started. The motor concurrently actuates the feeder foot 69, reciprocates the electrode I3, and oscillates the folder blade 85. Each cycle of operations, during a revolution of cam 41, is as follows: While electrodes |3 are'raised from the work the presser foot 61 cooperates with feed dog 69 and holds the. several thicknessesof sheetswhile the ruiiler blade 85 scuiTs in the ruiile sheet M a fold perpendicular to the direction of feed. Thereafter, while the blade holds the fold in place the upper electrodes I3 descend upon the fold and hold it, under pressure from spring 53, while the blade B5 is retracted. The radio frequency voitage impressed upon the electrodes causes current to flow through the two walls of each of the one or more layers of material forming the folded area in sheet M and through each layer of the base sheet B, softening the material and spotwelding these parts together at one or more, and preferably two, small spaced welding defined by the electrodes, the degree of welding heat depending upon the voltage across the electrodes. The electrodes I3 then are rais-ed, thereby releas ing the welding sheets. rIhe feed dog presser foot then advance the work to make room at the welding zone for the next ruiile. The parts are so synchronized that the ruier blade 85 is in. retracted position while the weld is being and that the feed dog te has completed its action advancing each welded ruflie before the rufer blade forms the next succeeding ruffle.

rlhe apparatus of Figs. 3 and 4 functions similarly to that of Fig. l, with the exception that immediately prior to retraction of the electrodes I3 from the welding position the high frequency heating circuit is detuned by movement of plates 9S of the variable condenser V into the position shown in full lines in Fig. 4, thereby reducing the voltage between the electrodes and preventing arcing at the electrodes. The circuit remains in the detuned condition until the blade 85 has formed another fold and each electrode i3 has moved into pressing contact with the upper surface of the newly folded area.

Variations in the rate of application of energy to the material during the different stages of each cycle of operations also can be effected by modulating the oscillator tube in the high frequency generator, or in any other well-known manner.

One preferred form of spot-welded ruiiied article is illustrated in Fig. 8. In that figure the two sides Vof each layer of material forming each of the ruflles or folded areas F in the sheet M, one side of each layer forming an adjacent folded area F, and one or more layers of the base sheet B are permanently united by two spaced spot welds W of any suitable shape and size. The material at the unwelded portions of each folded area is unrestrained and free to assume a rounded shape throughout the remainder of the length of each fold. All portions of the ruflied thermoplastic article are free to yield or stretch under any tension exerted either longitudinally or laterally of the rows of spot weld-.s formed. By employing a folder guide 63 for folding over the margin of sheet M, and/or a folder guide 63 for folding over a margin of sheet B (see `Eig. l), each spot weld unites from four to six or more thicknesses of the thermoplastic material, as shown in Fig. 8. Preferably, the folded-over marginal portions of both the sheets M and B are of sufficient depth that each of the welds formed in a rutile unites'the same number of layers of dielectric material as the other weld or welds.

The tiny but tough spot welds enhance the appearance of the ruiiied article while at the same time providing adequate strength, and preserving in such article the normal resilience of the thermoplastic material from which the sheeting made, unrestrained by extraneous materials haring properties differing therefrom, such as non.-

yielding threads. All portions of each sheet M and B are entirely free from perforations and other sources of weakness.

Fig. 9 illustrates a form of the invention wherein each of one or more layers of a sheet-like element of a dielectric material has formed therein a succession of closely-spaced folded areas throughout its width and wherein each of one or more layers of a relatively narrow sheet-like base of a dielectric material is permanently united with each of said folded areas by means of one spot weld located midway between the margins of the reet-like element. By the use of a somewhat wider sheet-like base, two or more spot welds can be made in each folded area. By using a sheet-like base and sheet-like element of different colors, attractive color eifects and the effeet of sewing or gathering with colored threads are secured at each spot weld. Thus, a ruching or double-ruffle effect is secured in a unitary article. If desired, two or more narrow, longitudinally-spaced, sheet-like bases may be united with the sheet-like element.

Permanent unitary rufes may be made from single sheet-like elements. Thus, in one form of the invention illustrated in Fig. l0, by using only the sheeting M, the latter is provided with a ruffled margin wherein each fold is spot-welded in place, the welding uniting the two sides of each ruffled or folded area to each other and to a side of an adjacent folded area. The resultant product may be stored or used as such, or later may be united with a second sheet or film such as the sheet B, in a separate spot-Welding or other operation.

Fig. 1l illustrates another form of rufe which can be produced in accordance with the invention. The ruiiies are produced by well-known folder attachments now in use on standard sewing machines. Here each of the one or more rows of spot welds W unites portions of the sheet lVl at folded areas through three or more thicknesses of the dielectric material. Each folded area consists of a relatively flat mid-portion lill, two inwardly sloping end portions lll, and two outwardly flaring portions H2, the respective portions being welded together by spaced spot welds arranged in one or more rows. A base sheet B may be spot-welded to the folded sheeting, as in the case of the article shown in Fig. 8.

Fig. l2 illustrates still another form of ruffled article made with the use of the invention in connection with standard rufliing equipment, l-iere the base sheet B and the ruled sheet M are spotwelded at one or more spaced points W lying between adjacent ridges.

it will be understood that the invention is not limited to the ruflled articles specifically described, nor to the particular form of the process and apparatus for making the saine described. @n the contrary, numerous modifications are possible within the scope of the appended claims, whereby a unitary permanent ruffled article is made, and especially one wherein the sides of each ruilled area of each of one or more sheets are spot-welded together and to an adjacent folded area of such sheet at one or more spaced points, and, if desired, to one or more base sheets, and wherein the remainder of the sheet or sheets at each ruffled area is substantially unconiined and free to yield or stretch under stress.

Either or both of the sheet-like elements of thermoplastic dielectric material may replaced by a sheet-like element of a non-thermoplastic fibrous material in the form of a woven, knitted,

felted or other fabricV impregnated or coated withr 1 a thermoplastic dielectric material, and the rufs lies formed and spot-welded in the manner hereindescribed. Thus, a woven or knitted fabric made from yarns of cotton, wool, silk, glass or the like may be impregnated and/or coated in whole or in part withra film or body of a vvinyl resin or other thermoplastic dielectric material hereinbefore mentioned. Such composite article then is converted into the form of awelded ruffle or, if desired, is concurrently ruilled and secured to another elementof a thermoplastic dielectric material or of a non-thermoplastic material coated with a thermoplastic dielectric material by welding in the manner described. Also useful as the sheet-like elements and/or bases are the composite fabricsv made from yarns formed by compositing filaments or bers of a non-thermoplastic material such as cotton, etc., with filaments or iibers of a plasticized thermoplastic dielectric material.

The term sheet-like element and similar eX- pressions used in the claims are intended to designate sheets, films, webs, batts, and woven, knitted and other fabrics which are relatively small in one dimension.

This application is a division of my pending application, Serial No. 714,832, filed December 7, 1946, for an invention entitled Heat Sealed Article and Process and Apparatus for Making Same. now matured as Patent No. 2,555,409.

I claim:

1. Apparatus for producing-heat-sealed ruffies, which comprises at least one stationary electrode and at least one cooperating reciprocatable electrode; means for impressing a high frequency voltage upon said electrodes; meansfor intermittently moving successive portions of a sheetlike element of a dielectric material between and past said electrodes at a selected rate by a rapid succession of short movements and for discontinuing each such movement; means for moving the reciprocatable electrode at arapid selected rate toward. and from the other electrode and into and out of contact with'the dielectric material; resilient means for pressing the reciprocatable electrode into contact with dielectric material disposed between the electrodes; means correlating the material-moving means and the electrode-reciprocating means whereby the former is operative when the reciprocatable electrode is out of contact with the dielectric material; means including a slotted folder arm operatively interconnected with reciprocatable electrode for forming folds said material; means for reciprocating the folder arm into and out of the zone between said electrodes; and means correlating the movement of the folder arm with that of the reciprocatable electrode for `moving the former and the material carried thereby into folding position between the electrodes while the reciprocatable electrode is out of contact with the dielectric material and for retracting the folder arm from such folding position immediately after the reciprocatable electrode contacts the folded area made in the material by such folding movement of the folder arm.

2. Apparatus for producing heat-sealed ruffles, which comprises at least one stationary electrode and at least one cooperating reciprocatable electrode; means for impressing a high frequency voltage from a tuned circuit uponsaid electrodes;

means for intermittently moving successive portions of a sheet-like element Aof a dielectric material between said electrodes by' a'rapd SHC-' izfff cession of short. movements and for discontinu-4 ing each such movement; means for moving the reciprocatable electrode at a rapid selected rate toward and from the other electrode and into and out of contact with the dielectric material and for maintaining such Contact during a major portion of each cycle of reciprocation; resilient means for pressing the reciprocatable electrode into contact with the material disposed between the electrodes; means correlating the materialmoving means and the electrode-reciprocating means whereby the former is operative when the reciprocatable electrode is out of contact with i the dielectric material; means including a slotted folder arm operatively' interconnected with said reciprocatable electrode for forming folds in said material; means for reciprocating the folder arm into and out of the zone between said electrodes; means including a canrmember associated with the reciprocatable electrode and a rockable shaft associated with the folder arm for correlating` the Ymovement of such electrode and folder arm for moving the folder `arm and material carried thereby into folding position between the elecf f trodes while the reciprocatable 'electrode is out of contact with the dielectric material and forv retracting the folder arm from such folding posiv i tion immediately after the reciprocatable elecl trode contacts the folded area made in the material by such foldingmovement of the folder arm.

3. Apparatus for producing heat-sealed ruffles, which comprises at least one stationary elec-` s trode and at least one cooperating reciprocatable electrode; means for impressing a high frequency l voltage from a tuned circuit upon said electrodes; means for intermittently moving successive por-f tions of a sheet-like element of a dielectric material between said electrodes by a rapid suc-V f cession of shortmovements and for discontinuing each such movement; means for moving the reciprocatable electrode at a rapid selected ratev z toward and from the other electrode and into'and out of contact `with the'dielectric material and for maintaining such contact during a major portion of each cycle of reciprocation; resilientf means for pressing the reciprocatable electrode into contact with the material disposed between the electrodes; means correlating the materialmoving means and the electrode-reciprocating means whereby the former is operative when the reciprocatable electrode is out of contact with the dielectric material; means including a slotted' folder arm operatively interconnected with said reciprocatable electrode for forming folds in said material; means for reciprocating the folder arm into and out of the zone between said electrodes means correlating the movement of the folder arm with that of the reciprocatable electrode for moving the former and the dielectric material carried thereby into folding position between the electrodeswhile the reciprocatable electrode is out of Contact with the material and for retracting the folder arm from such position immediatetwo electrodes connected in a high frequency' l, tuned electric circuit for developing welding heat Within' said materia-l at said'hea't-'sealingv zone;A

means for reciprocating one of said electrodes into and out of pressing contact with said material and for maintaining such contact during a major portion of each cycle of reciprocation; folder means integrated with said feeder means for forming a succession of folded areas in successive portions of said element at said heatsealing zone; and means interconnecting and correlating said electrode-reciprocating means and said folding means for retracting the latter means from said zone when the reciprocatable electrode is in contact with the sheet-like element and for advancing the folder means into the sealing zone when such electrode is positioned remote from said zone.

5. Apparatus for producting heat-sealed ruffies, which comprises at least one stationary electrode and at least one cooperating reciprocatable electrode; means for impressing a highfrequency voltage upon said electrodes; means for intermittently moving successive portions of a sheet-like element of a dielectric material between and past said electrodes at a selected rate by a rapid succession of short movements and for discontinuing each such movement;

means for moving the reciprocatable electrode at l a rapid selected rate toward and from the said electrode and into and out of contact with the dielectric material, said means including a cam surface cooperating with the reciprocatable electrode and so constructed that the latter is in contact with the dielectric material for at least two-thirds of each cycle of reciprocation of such electrode; resilient means for pressing the reciprocatable electrode into contact with dielectric material passed between the electrodes; means correlating the material-moving means and the electrode-reciprocating means whereby the forof contact with the dielectric material and for vretracting the folder arm from such folding position immediately after the reciprocatable electrode contacts the folded area made in the material by such folding movement of the folder arm.

LEE C. HosFIEL'b.

References Cited in the file 0f this patent UNITED STATES PATENTS Number Name Date 1,249,292 Montgomery Dec. 4, 1917 2,322,298 Johnson June 22, 1943 2,427,372 Sigoda Sept. 16, 1947 2,432,412 Hacklander Dec. 9, 1947 2,477,040 Brown et a1 July 26, 1949 2,484,076 Collins Oct. 11, 1949 2,490,451 Magid Dec. 6, 1949 2,555,409 Hoseld June 5, 1951 OTHER REFERENCES Hoyler, An Electronic Sewing Machine, reprint from the August 1943 issue of Electronics. page 6.